Good stuff on this thread.
IMO, gigs like this are a no-no for anyone over roughly 24 unless there are benefits you can wangle.
When we did the Enterprise (four years ago now) we knew it was crap, but decided to do it because...
1. We wanted to strip the four-piece down to a duo for a laugh, and see if it could work (it did, kinda)
2. I wanted to lose my pedal-steel-in-front-of-a-real-audience cherry
3. A mate reckoned he could get a decent hand-held video out of it (he was as good as his word)
For travellers from far afield, alas I don't see any benefits at all... unless you can find another, better London gig the same weekend.
I sympathise with the OP's position, I've been the cynical one many times and it's a fine line between trying to share your hard-won experience for the good of the band and running the risk of being seen by the keener members as a negative influence.